Prognostic Significance of Resting Heart Rate and Use of β-Blockers in Atrial Fibrillation and Sinus Rhythm in Patients With Heart Failure and Reduced Ejection Fraction

<jats:sec> <jats:title>Background—</jats:title> <jats:p>In heart failure and reduced ejection fraction, the prognostic role of heart rate (HR) in atrial fibrillation (AF) is unknown and the effectiveness of β-blockers has recently been questioned in AF.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods and Results—</jats:title> <jats:p> A total of 18 858 patients with heart failure and reduced ejection fraction registered with Swedish Heart Failure Registry were included in this study: patients with sinus rhythm (SR; n=11 466) and patients with AF (n=7392). The outcome measure was all-cause mortality. Compared with HR ≤60 beats per minute, the adjusted hazard ratios for mortality in SR were 1.26 for HR=61 to 70 beats per minute, 1.37 for HR=71 to 80 beats per minute, 1.52 for HR=81 to 90 beats per minute, 1.63 for HR=91 to 100 beats per minute, and 2.69 for HR >100 beats per minute. However, in AF, the hazard ratio increased only for HR >100 beats per minute (1.30; <jats:italic>P</jats:italic> =0.001). β-blocker use was associated with reduced mortality in SR (hazard ratio, 0.77; <jats:italic>P</jats:italic> =0.011) and in AF (hazard ratio, 0·71; <jats:italic>P</jats:italic> <0.001). For β-blocker use in SR, the hazard ratio gradually increased with HR increment, whereas in AF, the hazard ratio significantly increased only for HR >100 beats per minute (1.29; <jats:italic>P</jats:italic> =0.003) compared with HR ≤60 beats per minute. </jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions—</jats:title> <jats:p>In patients with heart failure and reduced ejection fraction, a higher HR was associated with increased mortality in SR, but in AF, this is true only for HR >100 beats per minute. β-blocker use was associated with reduced mortality both in SR and in AF.</jats:p> </jats:sec>